1. Field of the Invention
The present invention relates to a manufacturing method of a so-called SOI (silicon on insulator) having an SOI structure in which a semiconductor layer is provided on an insulating surface, and a manufacturing method of a semiconductor device having an SOI structure.
2. Description of the Related Art
Integrated circuits have been developed, which use a semiconductor substrate called a silicon-on-insulator (hereinafter also referred to as an SOI) which has a thin single-crystal semiconductor layer over an insulating surface, as an alternative to a silicon wafer that is manufactured by thinly slicing an ingot of a single-crystal semiconductor. An integrated circuit using an SOI substrate has been attracting attention because parasitic capacitance between drains of the transistors and the substrate is reduced and the performance of the integrated circuit is improved.
As a method for manufacturing SOI substrates, a hydrogen ion implantation separation method is known (for example, see Reference 1: Japanese Published Patent Application No. 2000-124092). The hydrogen ion implantation separation method is a method in which hydrogen ions are implanted into a silicon wafer to form a microbubble layer in the silicon wafer at a predetermined depth from a surface thereof, the microbubble layer is used as a cleavage plane, and a thin silicon layer is bonded to another silicon wafer. In addition to heat treatment for separation of the silicon layer, it is necessary to form an oxide film on the silicon layer by heat treatment in an oxidative atmosphere, remove the oxide film, and perform heat treatment at 1000 to 1300° C. to increase the bonding strength.
On the other hand, a semiconductor device in which a silicon layer is formed over an insulating substrate such as high heat resistant glass is disclosed (for example, see Patent Document 2: Japanese Published Patent Application No. H11-163363). The semiconductor device has a structure in which an entire surface of crystallized glass, a strain point of which is greater than or equal to 750° C., is protected by an insulating silicon film and the silicon layer obtained by hydrogen ion implantation separation method is firmly fixed over the insulating silicon film.